Field of the Invention
The present invention relates to an imprint apparatus, an imprint method, and an article manufacturing method.
Description of the Related Art
Imprint technique is a technique that enables transfer of fine nanoscale patterns. This technique is being put to practical use as a nanolithography technique that is applicable to mass production of magnetic storage media and semiconductor devices. In the imprint technique, a fine pattern is formed on a substrate such as a silicon wafer or a glass plate by using, as an original, a mold with a fine pattern formed by an apparatus such as an electron-beam drawing apparatus. The fine pattern is formed by dispensing an imprint resin onto the substrate and curing the resin while the resin and the pattern on the mold are pressed together.
Imprint techniques currently in practical use are a heat-cycle method and a photo-cure method. In the heat-cycle method, a thermoplastic imprint resin is heated to a glass transition temperature or higher to increase fluidity of the resin. Then, the resin and the mold are pressed together. After cooling, the mold is separated from the resin and thus a pattern is formed. In the photo-cure method, in which a photo-curable (ultraviolet (UV)-curable) imprint resin is used, the resin is cured by UV irradiation while the resin and the mold are pressed together. The mold is then separated from the cured resin and thus a pattern is formed. Note that in the present application, an uncured photo-curable imprint resin (e.g., monomer resin) will also be referred to as a resin, for simplicity. The heat-cycle method, which involves controlling the temperature of resin, requires a long transfer time. Moreover, changes in resin temperature cause changes in resin dimensions. The photo-cure method does not suffer from such problems and thus is advantageous in mass production of nanoscale semiconductor devices.
Up to the present, various imprint apparatuses have been realized in accordance with various resin curing methods and applications. For mass production of semiconductor devices etc., it is effective to use an apparatus that is capable of repeating dispensing of imprint resin and transfer of a pattern for each imprint region (also referred to as a shot region) on the substrate. Japanese Patent No. 4185941 discloses such an imprint apparatus. This imprint apparatus includes units for substrate positioning, resin dispensing, resin molding, light irradiation, and alignment measurement.
A resin used in the imprint apparatus disclosed in Japanese Patent No. 4185941 is dispensed onto the substrate by a dispenser. Dispensers commercially available today have a plurality of ports arranged in one row. For imprinting on a region that is equal in size to a maximum shot region for an exposure apparatus (e.g., a maximum exposure region of 33×26 mm2) currently available, a dispenser having a plurality of ports arranged over a length of 33 mm or 26 mm is suitable.
Since semiconductor devices vary in size, the actual exposure region will not necessarily be of the same size as the maximum exposure region of 33×26 mm2. The same applies to the imprint apparatus. That is, even if the imprint apparatus has a dispenser capable of dispensing a resin over a length of 33 mm or 26 mm, all ports of the dispenser may not necessarily be used all the time.
Due to demand for high-speed filling of resin into the mold, a UV-curable resin of high volatility can be used as an imprint resin. Therefore, if ports are not used for a long period of time (e.g., several hours), the resin in the ports vaporizes almost entirely. However, the resin does not completely disappear and the ports may be clogged with residual resin. If some ports are not used for a long time, uniform dispensing of resin may not be achieved. Therefore, to use such ports again, it is necessary to discharge resin from the ports multiple times before dispensing of resin onto the substrate. This discharge operation may be referred to as “idle discharging”.